146 BRITISH DESMIDIACE^. 



and Bohemia (var.). Italy. Norway. Sweden. 

 Greenland. Spitzbergen. Nova Zembla. United 

 States. 



C. cyclicum Lund, differs from C. undulatum Corda in its 

 more depressed semicells with less rounded basal angles, and 

 in the possession of two pyrenoids in each chloroplast. 



Var. arcticum Nordst. (PL LVIII, fig. 10.) 



C. cyclicum Lund, subsp. arcticum Nordst. Desm. Spetsb. 1872, p. 31, t. 6, 

 f . 13 ; Desm. Ital. 1876, p. 37 ; Boldt, Desm. Gronl. 1888, p. 22 ; De Toni, 

 Syll. Alg. 1889, p. 983 ; Eoy & Biss. Scott. Desm. 1894, p. 44 ; Borg. 

 Fresliw. Alg. Ostgronl. 1894, p. 15. 



C. cyclicum Lund. var. maculatum Sclimidle, Weit. Beitr. Algenfl. Rheineb. 

 11. Schwarzwald. 1895, p. 76, t. 1, f. 7. 



Cells subcircular, inclined to be somewhat sexanoai- 



' o 



lar ; semicells with the crena3 of the margin and within 

 the margin bigranulate (as if emarginate), those towards 

 the base unigranulate, apex 4-crenate and without 

 granules. 



Length 57'5-75jn; breadth 65-75 /x; breadth of 

 isthmus 22-28 p ; thickness 33-37 p. 



SCOTLAND.- -Aberdeen, Kincardine, Forfar, and Ren- 

 frew (Roy fy Bissett). 



Geogr. Distribution. G-alicia and Bohemia in Austria. 

 Italy. Norway. Bornholm. Poland. Faeroes. 

 Greenland. Spitzbergen. Nova Zembla. 



The figure of this variety given by Roy and Bissett is not 

 like that of Nordstedt's, hnt it suggests var. arcticum in the 

 minute binate granules. We give a copy of Roy & Bissett's 

 figure (PI. LVIII, fig. 11), and we think it stands near to var. 

 Nordstedtianum, as the granules are not evident at the margin. 



The form described by Schmidle as " var. maculatum ' is 

 intermediate in character between the figure given by Nord- 

 stedt and that given by Roy & Bissett. 



Var. Nordstedtianum (Reinsch) nob. (PI. LVIII, 



fig. 12.) 



Cosmarium Nordstedtianum Reinsch, Contrib. Alg. et Fungi, 1875, p. 89, 



t. 10, f. 11. 

 C. cyclicum Lund. var. angulatum West, Alg. N. Yorks. 1889, p. 293, 



t. 291, f. 2; Alg. Eng. Lake Distr. 1892, p. 728; West & G. S. West, 



Alga-fl. Yorks. 1900, p. 69. 



